A survey on frequency of insect bite hypersensitivity (IBH) in horses of Khuzestan province, Iran

Insect bite hypersensitivity is a recurrent and chronic dermatitis in horses, that is mainly caused by an allergic reaction to the bites of Culicoids species, and therefore in areas where these insects can grow, the risk of getting the disease also increases. The conditions in Khuzestan province (located in southwestern of Iran) are mostly hot and humid, causing many veterinarians to encounter horses with IBH symptoms. The present study aimed to evaluate the frequency of insect bite hypersensitivity among horses in this province. The study was performed on 255 Arabian horses kept in 21 horse breeding centers located in 6 cities of this province. The horses were examined for the presence or absence and location of skin lesions, along with the individual animal information, which was recorded in relevant forms. The prepared serum samples (32 healthy horses and 61 affected horses) were evaluated for total IgE using the ELISA test according to the instructions of the kit manufacturer. The results showed that 144 (56.5%) out of totally 255 horses had clinical signs of IBH. Statistical evaluations also revealed that among the hosting factors (including age, gender, bloodline, coat color, body condition score, and type of use), and management and environmental factors (including stud size, methods of control of insect, distance from the horse breeding centers to the water source, times of fecal collection in the horse breeding centers and the geographical location of the horse breeding centers), only stud size had a significant effect on the prevalence of IBH, In other cases, there was no significant relationship between the prevalence of the disease and the evaluated factor. The results also showed that the amount of IgE in affected horses was higher than in healthy horses. The results of this study showed that insect bite hypersensitivity exists with a significant frequency among horses kept in the horse breeding centers in Khuzestan province.